1. Field of the Invention
The present invention relates generally to methods of injection molding and a tool for forming injection molded parts. More particularly, the present invention relates to a method of injection molding parts with two molding steps and injection molding tools to make molding more efficient.
2. Description of the Related Art
Injection molding is one of the most popular processes for manufacturing plastic products. A typical injection molding process generally includes (1) injecting molten plastic material into a closed mold, (2) allowing the plastic to cool down and solidify, and (3) ejecting the finished product from the mold. This process may be used to form molded plastic parts, including for example, be used to form housings and accessories for various electronic products.
In some cases, injection molding can also be used to place decorative features on the outer surfaces of a part. In other cases, plastic can be molded over an already molded part to produce, for example, parts having two or more different colors or formed of two or more different materials. Formation of such features may be accomplished in two molding steps.
For example, the first molding step can be used to form the part (as described above for example), and the second molding step can be used to create an outer layer around some or all of the part (or vice versa). By way of example, injection molding in two steps may be used to place a soft layer on top of a hard layer, a transparent layer on top of an opaque layer, or create multicolored layers. In some cases, this molding process can be used to form the structural walls of the enclosure.
When one machine and tool set molds both shots, the tool is typically known as double-shot tool. Transferring a molded part from a first tool to a second tool for the second shot is known as transfer molding. A basic process can include injection molding a part, transferring this molded part to a second tool, and molding the second component on the transferred part. The transfer process can add complexity as well as cycle time to the process.